On Sun, 3 Jun 2012, Avi Kivity wrote:
> On 06/01/2012 09:26 PM, Jan Kiszka wrote:
> >
> >> you suggesting we need a request_edge_threaded_only_irq() API? Thanks,
> >
> > I'm just wondering if that restriction for threaded IRQs is really
> > necessary for all use cases we have. Threaded MSIs do not appear to me
> > like have to be handled that conservatively, but maybe I'm missing some
> > detail.
> >
>
> btw, I'm hoping we can unthread assigned MSIs. If the delivery is
> unicast, we can precalculate everything and all the handler has to do is
> set the IRR, KVM_REQ_EVENT, and kick the vcpu. All of these can be done
> from interrupt context with just RCU locking.
There is really no need to run MSI/MSI-X interrupts threaded for
KVM. I'm running the patch below for quite some time and it works like
a charm.
Thanks,
tglx
----
Index: linux-2.6/virt/kvm/assigned-dev.c
===================================================================
--- linux-2.6.orig/virt/kvm/assigned-dev.c
+++ linux-2.6/virt/kvm/assigned-dev.c
@@ -105,7 +105,7 @@ static irqreturn_t kvm_assigned_dev_thre
}
#ifdef __KVM_HAVE_MSI
-static irqreturn_t kvm_assigned_dev_thread_msi(int irq, void *dev_id)
+static irqreturn_t kvm_assigned_dev_msi_handler(int irq, void *dev_id)
{
struct kvm_assigned_dev_kernel *assigned_dev = dev_id;
@@ -117,7 +117,7 @@ static irqreturn_t kvm_assigned_dev_thre
#endif
#ifdef __KVM_HAVE_MSIX
-static irqreturn_t kvm_assigned_dev_thread_msix(int irq, void *dev_id)
+static irqreturn_t kvm_assigned_dev_msix_handler(int irq, void *dev_id)
{
struct kvm_assigned_dev_kernel *assigned_dev = dev_id;
int index = find_index_from_host_irq(assigned_dev, irq);
@@ -346,9 +346,8 @@ static int assigned_device_enable_host_m
}
dev->host_irq = dev->dev->irq;
- if (request_threaded_irq(dev->host_irq, NULL,
- kvm_assigned_dev_thread_msi, 0,
- dev->irq_name, dev)) {
+ if (request_irq(dev->host_irq, kvm_assigned_dev_msi_handler, 0,
+ dev->irq_name, dev)) {
pci_disable_msi(dev->dev);
return -EIO;
}
@@ -373,9 +372,9 @@ static int assigned_device_enable_host_m
return r;
for (i = 0; i < dev->entries_nr; i++) {
- r = request_threaded_irq(dev->host_msix_entries[i].vector,
- NULL, kvm_assigned_dev_thread_msix,
- 0, dev->irq_name, dev);
+ r = request_irq(dev->host_msix_entries[i].vector,
+ kvm_assigned_dev_msix_handler, 0,
+ dev->irq_name, dev);
if (r)
goto err;
}
--
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